Push back seat chair

ABSTRACT

A push back seat chair has a seat mounted on two slides movable fore-and-aft of the chair in track structures on opposite sides of the chair. The track structures may be mounted on the chair frame so as not to move vertically but so that the rear portions of the track structures may swing transversely toward or away from the adjustment frame parts, thus enabling chairs to be mounted in arcuate rows of different radii. The rear parts of the slides are pivotally connected to the lower part of the chair back, the upper part of which is connected to the frame for both pivotal and vertical movements. The chair seat is pivoted on the slides and is controlled in its pivotal movement so as to occupy a position of use in which it is at a rearward-downward inclination conducive to comfort and to occupy a retracted position in which its front edge is relatively lower than when in its position of use but still not so low as to result in a forward-downward inclination. The seat pan and chair back are relatively less rigid than the frame, and have little but sufficient flexibility to permit enough warping or twisting to accommodate some misalignment of frame parts in mounting and thereby to prevent binding of relatively movable interengaging parts.

United States Patent [72] Inventor Raymond C. Barnes Temple, Tex.

[21] Appl. No. 742,881

[22] Filed July 5, 1968 [45] Patented Mar. 30, 1971 [73] Assignee American Desk Manufacturing Company Temple, Tex.

[54] PUSH BACK SEAT CHAIR 14 Claims, 12 Drawing Figs.

Primary Examiner Francis K. Zugel AttorneyBaldwin, Wight, Diller and Brown ABSTRACT: A push back seat chair has a seat mounted on two slides movable fore-and-aft of the chair in track structures on opposite sides of the chair. The track structures may be mounted on the chair frame so as not to move vertically but so that the rear portions of the track structures may swing transversely toward or away from the adjustment frame parts, thus enabling chairs to be mounted in arcuate rows of different radii. The rear parts of the slides are pivotally connected to the lower part of the chair back, the upper part of which is connected to the frame for both pivotal and vertical movements. The chair seat is pivoted on the slides and is controlled in its pivotal movement so as to occupy a position of use in which it is at a rearward-downward inclination conducive to comfort and to occupy a retracted position in which its front edge is relatively lower than when in its position of use but still not so low as to result in a forward-downward inclination. The seat pan and chair back are relatively less rigid than the frame, and have little but sufficient flexibility to permit enough warping or twisting to accommodate some misalignment of frame parts in mounting and thereby to prevent binding of relatively movable interengaging parts.

PATENTED HARBO 1971 SHEET 1 [1F 4 INVENTOR RAYMOND c. BARNES PUSll-I BACK SEAT CHAIR This invention relates to push back seat chairs, and more particularly to such chairs as are especially adapted for mounting in rows in theaters, auditoriums and the like.

Many types of chairs of this general class have previously been provided and are in common use. They are generally characterized by movability of the seat from a position of occupancy rearwardly to a retracted position, while still occupied, to provide increased aisle room in front of the chair to facilitate passage of persons through the aisle to and from seats in the same row. Such previously provided chairs have lacked at least some of certain desirable attributes, such as: adaptability to facile mounting of chairs in arcuate rows of different radii; maintenance of minimum aisle width as determined by movement of the chair back incident to retracting movement of the seat; freedom from binding of coacting parts despite unavoidable misalignment of frame parts resulting from uneven floor surfaces; and simplicity of construction.

An object of the present invention is to provide a push back seat chair of the general class referred to which is of simple and economical construction and which has such desirable attributes as indicated above.

Another object of the invention is to provide such a chair so constructed that a plurality of the chairs may readily be mounted in an arcuate row of a selected radius without requiring adjustment of the chairparts according to different row arcs or radii, the chair construction having, so to speak, a built-in or inherent adjustability to accommodate for mount- .ing a plurality of chairs, all of essentially the same construction, on different arcs.

Another object is to provide such a chair which has an inherent property of adapting itself to misalignment of frame parts resulting from uneven floor or other mounting surfaces so as to avoid binding or interference of relatively moving engaging parts.

Another object is to provide a chair of the character described in which the extended and retracted positions of the seat are so determined as to provide for maximum comfort of the user in both positions.

A further object is control of the movement of the chair back accompanying retraction of the seat so as to provide maximum effective aisle width when the seat is in its retracted position.

Other objects of the invention will become apparent from a reading of the following description, the appended claims, and the accompanying drawings, in which:

FIG. l is a schematic end elevational view showing the end chair of each of four consecutive rows of chairs, fore-and-aft of, e.g. an auditorium or theater, the chair in row I at the left being shown with a chair frame with the seat and back omitted, the chair in row II being shown with the seat and back in the normal positions assumed when occupied, the chair in row III showing the parts in the positions when the chair is not occupied and the seat is raised, and the chair in row IV being shown with the seat and back in the positions assumed when the seat is occupied and held in lowered position but pushed rearwardly, that is retracted, by a user in order to provide additional space in the aisle between rows III and IV;

FIG. 2 is a schematic top plan view showing three chairs in a row arranged on an arc, certain parts being shown out of proportion to their actual sizes for clarity of illustration; I

FIG. 3 is a fragmentary vertical section showing parts of a chair side frame, a seat pan, a chair back member and structure for mounting the seat pan to pivot about a transverse axis so as to raise to the row III position shown in FIG. I, and for mounting the seat pain so that it may slide or be retracted rearwardly, seat and back cushions being omitted, and the illustrated parts being shown in full lines in the positions assumed when the chair is occupied, and in dotted lines in the positions assumed when the seat is raised;

FIG. 4 is a fragmentary horizontal section on the line M of FIG. 3, showing parts in relative positions assumed when a chair is set up in a straight row, that is not on an are as shown in FIG. 2; t

FIG. 5 is a fragmentary vertical section similar to FIG. 3, but showing the seat pan and lower part of the back in the retracted position of the seat;

FIG. 6 is a fragmentary horizontal section showing equipment at the side of the chair opposite from that shown in FIG. 4 for mounting a seat pan;

FIG. 7 is a fragmentary elevation of means mounting the top of a chair back to the chair frame for pivotal and vertical sliding movements, as viewed as indicated by the line 7-7 in FIG.

FIG. 8 is a fragmentary top plan view of the mounting means as viewed as indicated by the line 8-8 in FIG. 7;

FIG. 9 is a fragmentary elevation of a seat mounting slide structure and its connection to the chair frame, the parts being shown in the positions occupied when the chair seat, not shown in this FIG., is in its extended position for occupancy;

FIG. 10 is a horizontal section on the line 10-10 of FIG. 9;

FIG. 11 is a vertical section on the line 11-11 of FIG. 9; and

FIG. 12 is a vertical section on the line 12-12 of FIG. 9, on an enlarged scale.

The invention may be embodied in push back seat chairs of various types and for use in different kinds of installations. The illustrative embodiment is a theater or auditorium push back seat chair in the use of which it is especially desirable that the chair seat may be retracted rearwardly to provide more transverse aisle space for patrons to pass between rows of seats while seats in the rearmost of two adjacent rows are occupied. Thus, as previously set forth. generally, FIG. 1 shows three positions of the seat and back in rows II, III and IV. Considered generally, each chair comprises a frame F, a seat S, and a back B. In the chair shown in row II of FIG. I, the seat S is lowered and extended forwardly, and the back is inclined upwardly-rearwardly from the rear of the seat, the parts thus being in normal condition for occupancy. To provide additional space in the aisle in front of a seat, the seat may be pushed rearwardly by the occupant, while still seated, to the retracted position of the seat in row IV accompanied by rearward swinging of the back B which is mounted on the frame F by a pin and slot connection PS adjacent to the extreme upper end of the seat. The back B is pivoted at Pl to a slide SI. which is mounted to slide in an upwardly-rearwardly inclined track structure TS. The seat S is pivoted on opposite sides at P2 to the slide SL, there being a track structure TS and a slide SL on each side of the chair.

In operation, broadly, and assuming the parts to be as shown in row II in FIG. 1, rearward movement or retraction of the seat S to provide additional aisle room is accomplished while the seat is still occupied by exerting rearward pressure on the seat which causes the slides SL to move rearwardly and upwardly in the track structures TS, the pivot connections Pl between the slides and the lower part of the back B swinging the back to a substantially vertical position as in row IV in FIG. 1. This swinging of the back B involves pivotal movement and slight vertical movement of the back with respect to the frame F which is permitted by the pin and slot connection PS. Comparison of the showings of the chairs in rows II and IV in FIG. 1 will establish that when the seat S is retracted the top of the back B does not move rearwardly but moves forwardly only slightly. The bottom of the back B moves rearwardly until the back is substantially vertical. Thus, the minimum clearance space in the aisle behind the back is not reduced and the clearance space between the front of the seat S and the chair in the next row in front is increased. Furthermore, by virtue of mechanism to be described, the position of the seat S is controlled so that when occupied it will have a rearwarddownward inclination conducive to comfort, and when retracted as shown in row IV the seat S will have less of such an inclination, and most important its front edge will not be so low as to cause the top of the seat to have a rearward-upward inclination. Also, when the seat is retracted, the angle between the seat and back B is reduced only slightly so that a scissorslike folding of the seat and back upon one another, which could cause discomfort, is avoided.

when the seat is not occupied, it is maintained in the partially raised position shown in row III in FIG. 1 by mechanism to be described later.

I-Iaving broadly outlined relationships of parts important to achieving the objects of the invention, a more specific description of the preferred embodiment now follows. There are two chair frame units F, one at each side of the chair. Each frame unit F includes a generally vertical but inclined frame member 1 and a foot 2, shown in FIG. I, secured to the floor or other supporting surface. Each frame F comprises an arm or arm rest 3 as is conventional, and additionally a support member 4 which extends forwardly from the substantially vertical member 1. In the form shown, the parts ll, 3 and 4 are formed as hollow rectangular tubes which are joined in any suitable manner as by welding.

The seat S includes a seat pan member SP, e.g. of sheet metal, which receives a cushion C shown only in FIG. 1. The seat pan SP comprises a bottom 5, upstanding sides 6, and a transverse reinforcing box section rib 7 at the rear.

The back B comprises a sheet metal back member BM which includes a back portion 8 and forwardly extending sides 9, the member BM being reinforced by a box section rib 10. As shown only in FIG. 1, the back member BM receives a back cushion BC.

For supporting the seat S and articulating the latter to the lower part of the back member BM, there is disposed on each side of the seat a track and slide unit comprising a track structure TS and a slide SL. Each track structure TS, as particularly shown in FIGS. 3, 5, and 9-12, comprises a web 11 and spaced parallel flanges 12, 12 formed to provide grooved tracks. The front end of each track structure is mounted on the frame support 4 by a fastener such as a rivet or screw 13, which maintains the front of the track structure against any substantial vertical or transverse movement but is just a little loose provide sufficient play to permit the track structure to swing about the fastener 13 transversely of the chair. This enables the rear of the track structure to be moved slightly away from the adjacent frame F to a variable degree as shown in FIG. 10, the purpose of this transverse swinging of the track structure being explained later. The rear of the track structure TS is floatingly supported for free transverse movement by means comprising a track structure car 14 which is connected by a pin, rivet or like fastener 15 to the lower end of a suspension link L, the upper end of which is fastened by a rivet or the like 16 to the frame vertical member I.

Since the frame F, link L, and track structure TS constitute, in effect, a three-bar linkage, the linkage is locked and there can be no relative angular movement between the parts in the plane of the linkage. However, the parts comprising the connection of the front of the track structure TS to the frame part 4 and the parts comprising the connection of the rear of the track structure to the frame part 1 are inherently movable laterally relatively to each other in the assembled ready-to-use construction. Looseness of the connections at the rivet 13, the rivet l and the rivet 16 as well as some flexibility of the link L enable the rear of the track structure to swing transversely away from or toward the frame part 1 to a slight degree as indicated in FIG. 10. This permits the track structure and the cooperating slide SL to assume positions such as to avoid binding of the operating parts when chairs are mounted in an arcuate row as shown in FIG. 2. Indeed, but for the slight transverse swinging movement of the track structures, it would not be possible to mount chairs along an arc without straining the parts, irrespective of causing any binding of movable parts. With the present invention, and because of the slight lateral swinging of the track structures TS, it is possible to mount the chairs in a row on an are having a radius of as little as 18 feet. It will be understood that these advantages are obtained when, as shown in FIG. 2, a single vertical frame part 1 serves to mount the parts of two contiguous chairs in a row.

As particularly shown in FIGS. 3, 5, and 9I2, each slide SL comprises a web 17 and two spaced parallel flanges 18 formed as grooved ball ways. A row of balls 19 is positioned between each way 18 and a contiguous grooved track 112 of the associated track structure T8, the balls 19 being held in spaced relation by a ball retainer or cage 20. Movement of the slide SL relative to the track structure TS is limited by engagement of a rubber or like stop 21 secured to the slide respectively with stop pins 22 and 23 secured to the associated track structure TS. Thus, retracting movement of the slide is limited by engagement of the cushion stop 21 with the track structure stop 23, and forward or extending movement of the slide is limited by engagement of the cushion stop 21 with the track structure stop 22. As a safety measure for preventing the slide from being withdrawn completely or beyond a predetermined point in the event the cushion stop 19 wears out or fails, the tracks 12, 12 are crimped inwardly at 24 as shown in FIG. 5 so as to be in the path of the rows of balls 19. Thus, if the slide SI. is not stopped in its normal rear limit position by the cushion stop 21 and stop pin 23, the rear end balls will engage the crimped-in supplemental stops 24 to arrest the rearward movement of the slide SL.

As previously outlined broadly, retraction of the seat S is accomplished by rearward-upward sliding of the slides 81. in the track structures TS, the slides SL pivotally carrying the seat pan at P2, and the lower part of the back B being swung rearwardly by virtue of the pivotal connection P1, the back pivoting about the pin and slot connection PS and also moving upwardly as is permitted by that connection. It is important that,

during such movements of the parts during seat retraction, the seat S should be lowered somewhat at its front, but not so much as to cause the seat to assume a reverse inclination from that in row II, FIG. ii. In the preferred arrangement, when the seat is retracted to its row IV position, its front edge is at such an elevation that the seat still has a rearward-downward inclination, but less than in row II. In other words, when the seat is in retracted position, its front edge is less high with reference to its rear edge than when in the row II position. Controlling of the seat positions is effected by control means generally designated CM mounted rearwardly of the seat pivot P2 as best illustrated in FIGS. 3 and 5. On each side of the chair and attached to the back member IBM is a cam 25 presenting a flat almostvertical but somewhat inclined cam face in the row [I position. This cam face is engageable by a follower roller 26 mounted on an ear 27 extending upwardly from the seat pan SP. Considering FIG. 3, which shows the seat S lowered and in extended or forward position, the roller 26 and cam 25 determine the seat position to be on the comfort inclination for normal occupancy with the chair back in a vertically lower position, as in row Il, FIG. I. When the seat is still held in its lowered position but is retracted as shown in FIG. I, row IV, and in FIG. 5, the roller 26 follows along the cam 25 so as gradually to reduce the rearward-downward inclination of the seat until the fully retracted position has been reached and the seat will then be at the maximum reduced inclination with the chair back in a vertically raised position as shown in row IV in FIG. 1.

The pin and slot connection PS previously referred to is important in permitting the desired relative movements of the parts outlined above. Additionally, this construction is of a particular form providing further advantages. As shown in FIGS. 7 and 8, a slot member 23 is fixed to the vertical frame part 1 and is formed with an undercut slideway 29 which receives the head 30 of a pin 31 mounted on the chair back member BM. The slot member 28 preferably is of nonmetallic, noise inhibiting and wear resistant material such as rigid polyvinyl chloride material. The pin 31 is slidable axially in two spaced bearings 32 and 33, the former being provided in a side edge 9 of the back member BM and the latter being provided by a bearing member 33 secured to the back part 8. A compression spring 34 surrounds the pin 31 and is interposed between the bearing 32 and a spring anchor 35 fixed to the pin 31. The spring anchor 3:? may be constituted by a so-called push-nut which may be slid onto the pin in one direction but when loaded by the spring 34 will grip the pin and remain in stationary position thereon.

In use, the spring 34 acts on the pin 31 through the anchor 35 to draw the pin axially inwardly toward the center of the chair, thus maintaining the pin head 30 in constant engagement with the overhanging portions of the undercut slideway 2 h. The pin and slot construction shown in FIGS. 7 and 8 is, of course, provided on each side of the chair so that the two springs 34 act in opposite directions and thus tend to maintain the chair back resiliently centered between the two frame parts i, 1. Furthermore, the spring urged pins 3i may move slightly as is required to enable assembling of a plurality of chairs in a row without binding which otherwise might result from slight misalignment of the frame parts I, 1, due, for example, to mounting the frame feet 2 on an uneven surface. It should be realized that if the rear part of a frame foot 2 should be raised by a small bump on a concrete floor as little as onefourth of an inch, the upper part of the frame F could be swung forwardly as much as three-fourths of an inch, or even more. Even such misalignment of a pair of frames F will not cause binding due to the flexibility of the pin and slot connections PS. v

Spring means are provided for normally maintaining the seat S in a partially raised position as shown in row III of FIG. I when not in use. As shown in FIGS. 3, 4 and 5, a spring-36 is coiled around the pivot pin P2, one end of the spring gripping the pin P2 to anchor that spring end, and the other end 36a of the spring being extended so as to be engageable by the seat pan bottom 5 when the seat pan is moved to its partially raised position. When the seat pan is in its partially raised position, the spring as tends to move the seat pan toward its lowered position, but such movement is resisted by a further spring 37 shown in H6. 6, which surrounds the pivot pin P2 on the opposite side of the chair from the spring 36 and has its free end 37a extended reversely to the spring extension 36a. Thus the spring 37 tends to swing the seat rearwardly from its partially raised position in row III of FIG. 1. It follows that the springs 36 and 37 act oppositely to one another so that the balanced spring action yieldably holds the seat in its partially raised position. However, the spring 37 can yield to permit lowering of the seat from its row III to its row II position, and the spring 36 can yield to pressure exerted rearwardly on the seat when in its partially raised row HI position to enable the seat to be swung further to the rear from that position.

Protective shrouds 38 are mounted on the seat back B for covering the control means CM provided by the cam 25 and roller 26 so as to prevent users from being injured and also to prevent cushions from interfering with the operation of the control means CM.

As previously stated, connection of the track structures TS to the frame by the suspension links L and slight looseness in the connections l3, l5 and 16 enables mounting of the chairs in arcuate rows and also permits adaptation of the parts to slightly varied positions as is required to prevent binding of relatively movable parts such as the pivot connections P1, P2 and PS and the sliding of the slides SL in the track structures TS.

' A chair in accordance with the present invention is constructed in a manner to prevent binding irrespective of the link suspensions L. The frames F are relatively rigid, but the seat pan SP and the back member BM are formed of sufficiently light or thin material to be relatively less rigid than the frame so that they may warp or twist almost imperceptibly as viewed by the eye, but nevertheless sufficiently to adapt the parts for smooth movements without binding. In the illustrative em bodiment, the frame F is substantially rigid, for all practical purposes. The seat pan SP is of sheet steel approximately 0.078-inch thick, approximately 17% inches from front to back, approximately 18% inches from side to side, and the sides 6 taper in width from about.2 inches at the back to about /1 inch in front. The back member BM is of sheet steel approximately 0.078-inch thick, approximately 23 inches from top to bottom, approximately 19 inches from side to side, the sides 9 tapering from about inch at the top to about 2% inches at the bottom, exclusive of the ears 27. This material and relative dimensions illustrate by way of example relations which enable the small amount of warping or twisting which is effective to prevent binding when the frame parts are somewhat misaligned due, for example, to irregularity of the floor or other mounting surface.

In reviewing some of the advantages flowing from the constructional features described above, it is pointed out that the described chairs are adapted for mounting in arcuate rows of a wide range of radii. When the seat is retracted by a seated occupant, the minimum effective clearance in the next aisle to the rear is not reduced. The seat returns by gravity from its lowered retracted position to its lowered extended position. When in its lowered retracted position, the seat has not assumed a forward-downward inclination but the front edge of the seat is lower relatively to the rear edge thereof than when the seat is in its lowered normal position of occupancy. Scissorslike action between the seat and. back when the seat is retracted is minimized, due in part to the location of the pivot PS near the extreme upper part of the back B and due to the upward movement of the back B during seat retraction. The control cam 25 and follower 26 determine the most comfortable and convenient seat positions when extended and lowered, and when retracted and lowered. Particularly important is that during seat retraction, the top of the back B does not move rearwardly and moves only slightly forwardly. The bottom of the back B moves rearwardly during retraction until it is vertically plumb with the top rear portion of the back. The relative flexibility of the seat pan SP and the back member BM enable these parts to warp or twist slightly so as to avoid bindingof the relatively movable engaging parts.

The construction illustrated and described embodies the invention in a preferred form, but the disclosure is intended to be illustrative rather than definitive, the invention being defined in the claims.

I claim:

1. In a push back seat chair, a frame; two track structures respectively on opposite sides of the chair; means mounting each track structure on the frame to extend fore-and-aft of the chair and including a front connection between the front part of said track structure and said frame, and a rear connection between the rear part of said track structure and said frame, both said connections preventing substantial vertical movement of said track structure relative to said frame, each of said front connections comprising a fastening device providing sufficient play between theassociated track structure and frame to enable the rear part of said track structure to move transversely of said chair while the front part of said track structure immediately adjacent said fastening device does not move substantially transversely of said chair, each of said rear connections comprising means connected between the rear part of said track structure and said frame to floatingly support the rear of said track structure for free transverse movement, thereby enabling small lateral substantially horizontal movement of the rear part of said track structure relative to said frame when said track structure and said frame are assembled in ready-to-use condition, thereby to permit variable lateral inclining of said track structure to the Ifore-and-aft line of said chair; slides mounted respectively in said track structures for fore-and-aft movement; a seat member mounted between said slides and pivotally thereon to rock about an axis transverse to the fore-and-aft line of the chair; a back member; first pivot means connecting a lower part of said back member to the rear parts of said slides; and means including second pivot means connecting an upper part of said back member to said frame.

2. A chair according to claim 1 in which each of said means connected between the rear part of the associated track structure and said frame comprises a suspension link connected at its lower end to the rear part of said track structure and connected at its upper end to said frame.

3. A chair according to claim 1 in which said track structures are mounted at a rearward-upward inclination to the horizontal.

d. A chair according to claim 1 in which said second pivot means is connected to said back member closely adjacent to the extreme upper end thereof.

5. A chair according to claim 1 in which one of said first and second pivot means comprises a slot component and a pin component enabling said back member to move vertically relatively to the part to which it is connected by said one of said pivot means as well as pivotally relatively thereto.

6. A chair according to claim 5 in which said pin component has a head and said slot component has an undercut slideway receiving said head.

'7. A chair according to claim 6 in which said slot component is formed of nonmetallic, noise inhibiting, wear resistant material.

8. A chair according to claim 1 in which said second pivot means is provided at each side of said chair, each of said second pivot means comprising a slot component mounted on said frame and having a slideway; a bearing mounted on said chair back; a pin mounted to slide axially in said bearing and having its end received in said slideway; and a spring interposed between said pin and a fixed part of said back and urging said pin axially into engagement with said slideway, the aforesaid springs, at opposite sides of said back, urging said pins oppositely to each other.

Q. A chair according to claim 1 in which the pivotal mounting of said seat member on said slides is spaced forwardly of said first pivot means and rearwardly of the front edge of the seat member, said chair further including mutually engageable control parts mounted respectively on said back member and said seat member for determining two lowered positions of said seat member, one of said positions being with said seat member extended forwardly with respect to said frame and at a rearward-downward inclination fore-and-aft of the chair and the other of said positions being with said seat member retracted rearwardly with respect to said frame and with the front edge of said seat member being lower relatively to the rear edge thereof than when said seat member is in said one of said positions.

if). A chair according to claim 9 in which said control parts determine said other of said positions of said seat member to be with said seat member devoid of any fore-and-aft downward inclination from the rear edge thereof to the front edge thereof.

11. A chair according to claim 9 in which said control parts include a substantially vertical cam track mounted on said back member above said first pivot means; and a cam follower on said seat member to the rear of said pivotal mounting of said seat member on said slides.

12. A chair according to claim 9 in which said track structures are mounted at a rearward-upward inclination to the horizontal, whereby said seat member will return by gravity from a rearward retracted position to a forward extended positron.

13. In a push back seat chair, a frame; two track structures respectively on opposite sides of the chair; means mounting each track structure on the frame to extend fore-and-aft of the chair at a downward rear-to-front inclination; slides mounted respectively in said track structure for fore-and-aft movement; a seat member mounted between said slides and pivotally thereon to rock about an axis intermediate the front and rear edges of said seat member and being transverse to the foreand-aft line of the chair; a back member; first pivot means connecting a lower part of said back member to the rear parts of said slides; second pivot means connecting said back member to said frame at a point closely adjacent the top of said back member, said second pivot means enabling approximately vertical as well as pivotal movement of the top of said back member relative to said frame; and mutually engageable control parts mounted respectively on said back member and said seat member rearwardly of the seat pivot for determining two lowered positions of said seat member, one of said positions being with said seat member extended forwardly with respect to said frame and at a rearward-downward inclination fore-and-aft of the chair with the back in a vertically lower position, and the other of said positions being with said seat member retracted rearwardly with respect to said frame with the back in a vertically raised position, and with the front edge of said seat member being lower relatively to the rear edge thereof than when said seat member is in said one of said positions and with said seat member being devoid of any fore-andaft downward inclination from the rear edge thereof to the front edge thereof.

14. A chair according to claim 13 in which said control parts include a substantially vertical cam track mounted on said back member above said first pivot means; and a cam follower on said seat member to the rear of said pivotal mounting of said seat member on said slides. 

1. In a push back seat chair, a frame; two track structures respectively on opposite sides of the chair; means mounting each track structure on the frame to extend fore-and-aft of the chair and including a front connection between the front part of said track structure and said frame, and a rear connection between the rear part of said track structure and said frame, both said connections preventing substantial vertical movement of said track structure relative to said frame, each of said front connections comprising a fastening device providing sufficient play between the associated track structure and frame to enable the rear part of said track structure to move transversely of said chair while the front part of said track structure immediately adjacent said fastening device does not move substantially transversely of said chair, each of said rear connections comprising means connected between the rear part of said track structure and said frame to floatingly support the rear of said track structure for free transverse movement, thereby enabling small lateral substantially horizontal movement of the rear part of said track structure relative to said frame when said track structure and said frame are assembled in readyto-use condition, thereby to permit variable lateral inclining of said track structure to the fore-and-aft line of said chair; slides mounted respectively in said track structures for foreand-aft movement; a seat member mounted between said slides and pivotally thereon to rock about an axis transverse to the foreand-aft line of the chair; a back member; first pivot means connecting a lower part of said back member to the rear parts of said slides; and means including second pivot means connecting an upper part of said back member to said frame.
 2. A chair according to claim 1 in which each of said means connected between the rear part of the associated track structure and said frame comprises a suspension link connected at its lower end to the rear part of said track structure and connected at its upper end to said frame.
 3. A chair according to claim 1 in which said track struCtures are mounted at a rearward-upward inclination to the horizontal.
 4. A chair according to claim 1 in which said second pivot means is connected to said back member closely adjacent to the extreme upper end thereof.
 5. A chair according to claim 1 in which one of said first and second pivot means comprises a slot component and a pin component enabling said back member to move vertically relatively to the part to which it is connected by said one of said pivot means as well as pivotally relatively thereto.
 6. A chair according to claim 5 in which said pin component has a head and said slot component has an undercut slideway receiving said head.
 7. A chair according to claim 6 in which said slot component is formed of nonmetallic, noise inhibiting, wear resistant material.
 8. A chair according to claim 1 in which said second pivot means is provided at each side of said chair, each of said second pivot means comprising a slot component mounted on said frame and having a slideway; a bearing mounted on said chair back; a pin mounted to slide axially in said bearing and having its end received in said slideway; and a spring interposed between said pin and a fixed part of said back and urging said pin axially into engagement with said slideway, the aforesaid springs, at opposite sides of said back, urging said pins oppositely to each other.
 9. A chair according to claim 1 in which the pivotal mounting of said seat member on said slides is spaced forwardly of said first pivot means and rearwardly of the front edge of the seat member, said chair further including mutually engageable control parts mounted respectively on said back member and said seat member for determining two lowered positions of said seat member, one of said positions being with said seat member extended forwardly with respect to said frame and at a rearward-downward inclination fore-and-aft of the chair and the other of said positions being with said seat member retracted rearwardly with respect to said frame and with the front edge of said seat member being lower relatively to the rear edge thereof than when said seat member is in said one of said positions.
 10. A chair according to claim 9 in which said control parts determine said other of said positions of said seat member to be with said seat member devoid of any fore-and-aft downward inclination from the rear edge thereof to the front edge thereof.
 11. A chair according to claim 9 in which said control parts include a substantially vertical cam track mounted on said back member above said first pivot means; and a cam follower on said seat member to the rear of said pivotal mounting of said seat member on said slides.
 12. A chair according to claim 9 in which said track structures are mounted at a rearward-upward inclination to the horizontal, whereby said seat member will return by gravity from a rearward retracted position to a forward extended position.
 13. In a push back seat chair, a frame; two track structures respectively on opposite sides of the chair; means mounting each track structure on the frame to extend fore-and-aft of the chair at a downward rear-to-front inclination; slides mounted respectively in said track structure for fore-and-aft movement; a seat member mounted between said slides and pivotally thereon to rock about an axis intermediate the front and rear edges of said seat member and being transverse to the fore-and-aft line of the chair; a back member; first pivot means connecting a lower part of said back member to the rear parts of said slides; second pivot means connecting said back member to said frame at a point closely adjacent the top of said back member, said second pivot means enabling approximately vertical as well as pivotal movement of the top of said back member relative to said frame; and mutually engageable control parts mounted respectively on said back member and said seat member rearwardly of the seat pivot for determining two lowered positions of said seat member, one of said Positions being with said seat member extended forwardly with respect to said frame and at a rearward-downward inclination fore-and-aft of the chair with the back in a vertically lower position, and the other of said positions being with said seat member retracted rearwardly with respect to said frame with the back in a vertically raised position, and with the front edge of said seat member being lower relatively to the rear edge thereof than when said seat member is in said one of said positions and with said seat member being devoid of any fore-and-aft downward inclination from the rear edge thereof to the front edge thereof.
 14. A chair according to claim 13 in which said control parts include a substantially vertical cam track mounted on said back member above said first pivot means; and a cam follower on said seat member to the rear of said pivotal mounting of said seat member on said slides. 